Visual Programming Languages (hereinafter referred to as “VPL”), which display a program in a visually understandable manner, for example, using a flowchart, a function block diagram, or the like, are prevalent (For example, Japanese Unexamined Patent Application Publication No. 2005-309593 and Japanese Unexamined Patent Application Publication No. 2005-242682).
In VPL, programs are created in a display space provided by a programming editor. In the display space, relationships between program objects are established, for example, by placing program objects in the display place, connecting the program objects with a connection line, and the like.
Compared with other non-VPL programming languages, such as C, VPL is advantageous in that a program content can be instinctively understood and is easier to edit.